It is often desirable to filter fluid-borne contaminants from the flow of a pressurized fluid. For example, filtering is often advantageously employed in a fuel line that delivers a combustible fuel to an engine combustion chamber, as the presence of contaminants in the combusted fuel can adversely affect engine performance.
Another application where filtering is sometimes employed is in a pressure relief system used to sense and relieve over pressure conditions in a transported fluid. A commonly employed pressure relief system configuration such as exemplified by U.S. Pat. No. 6,457,697 issued to Kolze utilizes a main valve assembly to provide a bypass path for the pressurized fluid.
The main valve is actuated by a pilot valve assembly which employs a number of small, precisely sized orifices to permit controlled flow of a portion of the fluid. An upstream filtering screen removes fluid-borne contaminants from the fluid to prevent clogging of the orifices, since a partially or fully blocked orifice can detrimentally affect operation of the main valve assembly.
Regardless of the application, it is often difficult to gauge the effectiveness of a particular filtering system at any given time. In systems that employ replaceable filter elements, it is common to periodically replace the elements on a scheduled basis. To be effective, such an approach typically requires rigorous human intervention which can be subject to variations and oversights.
Moreover, depending upon the application, contaminant levels in fluids can change over time. Thus, a particular filter element may fill to capacity and thereafter provide insufficient filtering long before the next scheduled replacement.
There is therefore a continued need for improvements in the filtering of fluid-borne contaminants from a fluid, and it is to such improvements that the present invention is directed.